The log lines are related to an index request (no path provided in the URI). They indicate that such a request matches the pattern of “does not contain /index.php/”, and does not match the criteria of “is not a directory”. The input “/var/www/html//” is a valid directory.
Do you have DirectoryIndex index.php set in your virtualhost? This enables Apache to respond to a directory request with the index.php file it contains.